A client taking methimazole reports a sudden onset of fever and sore throat. What is the priority action the nurse should take?

Methimazole is an antithyroid thionamide that inhibits thyroid hormone synthesis by blocking thyroid peroxidase. A serious adverse effect is agranulocytosis, characterized by severe neutropenia leading to immunosuppression, infection risk, sudden fever, and sore throat, requiring immediate drug discontinuation and urgent evaluation of white blood cell count. Rationale: A. Administering Tylenol may temporarily reduce fever, but it masks a potential life-threatening complication of agranulocytosis. Symptomatic treatment delays recognition of neutropenia and does not address the underlying bone marrow suppression caused by methimazole. B. Continuing methimazole despite fever and sore throat increases risk of severe infection and sepsis. Agranulocytosis can progress rapidly, so delaying intervention places the client at significant risk of life-threatening hematologic complications. C. Increasing fluids may support hydration but does not address suspected bone marrow suppression. These symptoms require immediate cessation of the drug and diagnostic evaluation rather than supportive care alone. D. Sudden fever and sore throat in a client taking methimazole indicate possible agranulocytosis, a medical emergency. Immediate discontinuation of the medication and notification of the provider are essential to prevent progression to severe infection and potential septic complications.